ALICE Inner Tracking System Upgrade at the LHC

Abstract

The design objective of ALICE is to study the properties of the Quark–Gluon plasma using the pp, p–Pb, and Pb–Pb collisions at the LHC. Using the excellent tracking and particle identification capability, ALICE has achieved several milestones in understanding the hot and dense nuclear matter produced in these collisions. During the long shutdown period in 2019–20, ALICE will undergo a major upgrade to improve its precision of the present physics measurements. As part of this upgrade plan, the ALICE Inner Tracking system (ITS) will significantly be upgraded to enhance its capabilities to measure the rare probes with greater precision. The key goal of the ITS upgrade is the construction of a new detector with high resolution, low material budget, and high read-out rate. This upgrade will enable to collect data at the rate of 400 kHz and 50 kHz in pp and Pb–Pb collisions, respectively, during the LHC high luminosity program in Run 3. The new ITS detector has 7 concentric layers of CMOS pixel detector based on Monolithic Active Pixel Sensor (MAPS) technology and is designed to achieve all these requirements. It is one of the first applications of MAPS technology in a high-energy physics experiment. This MAPS-based sensor, with other stringent mechanical design of the detector support material, will reduce the material budget to 0.3\(\%\) X\(_{0}\) for the inner layers and 1\(\%\) X\(_0\) of the outer layers. In this presentation, we will discuss the design goal, layout of the new detector, its performance during the research and development phase, and the production status.